import java.util.LinkedHashMap;
import java.util.Map;

/**
 * @author zhangdi
 * @version 1.0
 * @date 2022.1.28 14:59
 */
public class HashTest {
    public static void main(String[] args) {
//        String.valueOf()
//        Map<String, Object> map = new LinkedHashMap<>();
//        map.put("id", null);
//
//        System.out.println((Long) map.get("id"));
    }
}
